@Fido,
I actually think etiquette is a very interesting subject. It's sort of like "mini-morality". I think this is a good fit for the ethics forum. Usually it isn't discussed at all, people just say "this is rude, this isn't".
People disagree on this forum, so perhaps they should put their ideas up for debate. Is it ok to be rude to people for "being foolish" or "not posting a decent argument"? I believe HexHammer in his thread referred to it as "bursting naive peoples' bubbles".
I think a lot of rudeness comes from enforcing rules of etiquette, ironically. Like the spelling example earlier, or the bits about dismissing someones argument for not being up to forum standards. I've seen people (on other forums mostly) be angry just because someone is
wrong about something.
Maybe that's just fine for them, but from my own experience, when I'm rude it's either by accident or because I've gotten miffed about something (usually someone else being rude, or me perceiving it that way). It just seems better to relax and not have as strict a rule set. Why let things get to you if you can help it? Bickering isn't exactly pleasant and doesn't accomplish much.